The current manner of processing discarded vegetation and wood, referred to as green waste, entails grinding the green waste in one device and then sifting or screening the usable material in another device; generally an open-top tub-like grinder, referred to as a tub grinder, having large hammers, teeth or blades impacting material under very high torque. The device operates in a blender-like fashion. Problems associated with this method include the generation and release into the environment of volumes of dust and debris, movement of large volumes of ground material to another device for screening processed waste, and limited sifting and sorting options. Plastic container bags of green waste must be opened and trash therein sorted before being placed into a grinder. The grinder also receives grass, sand, dust, and other small particles not requiring grinding by such a device. This grass, sand, dust, and smaller particles cause excessive wear on the grinder due in part to the moisture or coarseness of the material.
Green waste is loaded into the tub grinder from the top. In addition to the hammer and teeth or blades, the grinder relies on gravity and the weight of the material in its processing. Because of this operating principal, the motor to operate this grinder and turn the grinding tools burdened by the weight of the materials thereon must be extremely powerful. In spite of its power, it is not suited for fibrous materials such as palm tree waste (palms, trunk, and bark) and yucca plants and moist material such as ice plant and grass. These green waste materials cause the grinder generally to become impeded in its operation or to jam.
In addition, this grinder is costly to manufacture and is expensive to operate. Excessive jamming and down time adversely affect its efficiency and effectiveness. Because huge quantities are loaded into the grinder from the top, it is difficult to screen out unsuitable green waste. Large metal objects or rocks can damage or break the hammer and teeth. To provide for such screening requires manpower thereby further increasing the cost of operation.
Though the grinder can process such material quickly, it generally does so much more quickly than most recycling processing centers receive such material to process. Because of this, and because of the costs to maintain and to operate the grinder, these recycling processing centers usually collect and stockpile their green waste until'such time that a sufficient volume has been received to make operation of the grinder cost-efficient. Grinding, therefore, is periodic. These delays in processing result in a decomposition of the material with the concomitant creation and emission of unpleasant odors. The present invention processes the material as it is received and aerates the processed material thereby precluding the creation and emission of unpleasant odors.
Another waste processor is found in U.S. Pat. No. 3,930,799, issued to Eweson on Jan. 6, 1976. This apparatus is designed for producing organic fertilizer by fermentation. It provides for a large rotatable drum and a series of blades and chains within to grind materials placed therein. It best operates with several compartments within the drum to permit the ground material to stand and ferment and to pass through apertures between the inner compartments to the next compartment. Excluded from processing are materials such as wood. The drum, with its interior configuration, is designed to rotate slowly, about 10-60 revolutions per hour. The Eweson apparatus is not suited for green waste and wood materials.
U.S. Pat. No. 3,614,003 issued on Oct. 19, 1971, to Tremolada processes scrap lead batteries. It has a rotatable drum with a decreasing diameter from beginning to end, lifting wings (or platforms) for lifting the batteries and dropping and crushing them against the opposite side wall of the drum as it rotates, a continuous spiral bar to move the material within from front to rear as it processes, and a screening means to permit passage of finely processed materials. This device, like the prior patented apparatus is not suited for processing green waste and wood.